Similarly Euler-Lagrange (EL) systems can have uncertainties with LIP or NLIP (e.g. system with nonlinear friction ([1]})) structure. However, the upper bound of the overall (or lumped) uncertainty for such systems has LIP property [2]}. EL systems, in general, represent a large class of real world systems like robotic manipulators [3]}-[4]}, mobile robots [5]}, ship dynamics, aircraft, pneumatic muscles [6]} etc. These systems have immense applications in various domains such as defence, automation industry, surveillance, space missions etc. The controllers [7]}-[8]} assume that the overall uncertainties are upper bounded by some constant, while [9]}-[10]} assume the time derivative of the overall uncertainty to be bounded by some constant. Hence, for the aforementioned class of systems, consideration of such constant bound (known or unknown) restricts the system state a priori. Further, the switching gain in [11]}-[8]} suffers from over- and under-estimation problems. In practice, it is also not always possible to have prior knowledge of bounds for system parameters as required in [13]}, [14]}-[15]} for projection operator.
